In R ( Bridges) v South Wales Police (2020) EWCA Civ 1058 the Court of Appeal said at para 176 that, albeit the PSED is a process duty, not an outcome duty, that does not diminish its importance. The Court observed that public law is often concerned with the process by which a decision is taken, for two reasons : (1) good processes are more likely to lead to better informed, and therefore better, decisions; (2) whatever the outcome, good processes help to make public authorities accountable to the public.
At para 179 the Court of Appeal said that why the PSED is important is that it requires a public authority to give thought to the potential impact of a new policy which may appear to it to be neutral but which may turn out in fact to have a disproportionate impact on certain sections of the population.
At para 181 they said that what the PSED requires is the taking of reasonable steps to make enquiries about what may not yet be known to the public authority about the potential impact of a proposed decision or policy on people with the relevant characteristics.